This invention is generally directed to toner compositions, and more specifically, the present invention relates to developers comprised of toner compositions comprised of low melt resin particles. In one embodiment, the present invention relates to a toner composition comprised of hydrogenated resin particles, colorants, such as known pigment particles, and optional additives, such as charge control components. In another embodiment of the present invention, the toner composition can be hydrogenated to, for example, improve its blocking and release characteristics. More specifically, in one embodiment of the present invention there are provided developer compositions formulated by, for example, admixing low melting, about 220.degree. F. to about 300.degree. F., toner compositions hydrogenated with, for example, hydrogen or diimide, and carrier components. In another embodiment of the present invention, there are provided toner compositions with hydrogenated toner resins containing polymers prepared by bulk, solution, free radical, anionic, suspension, dispersion, or emulsion techniques, such as random or block copolymers (A-B).sub.n wherein n represents the number of repeating polymer segments and where A and B represent monomeric or oligomeric segments of, for example, styrene and butadiene, respectively, which components possess in embodiments of the present invention a desirable low fusion and low fusing energy; are easily jettable or processable into toner compositions; enable low temperature fusing; are optically clear; allow matte and gloss finishes; and with the toner resins illustrated herein there can in embodiments be fabricated brittle, rubbery, or other similar toner polymers with an optimized melt viscosity profile, and a lowering of the fusing temperature characteristics of the toner resin can be achieved. The hydrogenated toner polymers of the present invention can be processable by conventional toner means, that is these materials are extrudable, melt mixable and jettable. The toner compositions in embodiments of the present invention possess lower fusing temperatures, and therefore, lower fusing energies are required for fixing, thus enabling less power consumption during fusing, and permitting extended lifetimes for the fuser systems selected. Moreover, high gloss images may be obtained at lower fuser set temperatures. The toners of the present invention can be fused at temperatures (fuser roll set temperature) of between 220.degree. and 320.degree. F. in embodiments of the present invention as compared to a number of currently commercially available toners which fuse at temperatures of from about 300.degree. to about 370.degree. F. With further respect to the present invention, the ultra low melt resins have, for example, in embodiments thereof a glass transition temperature of from about 24.degree. to about 80.degree. C. and in embodiments employing cryogenic jetting conditions, glass transition temperatures of from about 0.degree. or less to about 24.degree. C. Known nonblocking characteristics, that is noncaking or retaining substantially all the properties of a free flowing powder at temperatures of, for example, about 120.degree. F. or less are obtained with the toner compositions of the present invention in embodiments thereof. Further, the treated toner compositions of the present invention can be selected for single component development in that, for example, the toners resist smearing, and do not form toner aggregates under the pressure stresses usually selected for such development systems. Also, toner compositions containing the hydrogenated resins illustrated herein can include wax components such as on the surface to improve the release characteristics of the toner. In embodiments of the present invention, the wax component can be situated on the surface of the toner by hydrogenation of unsaturated olefin groups on the surface of the toner particles. These toners (referred to as H-Shell toners) possess shells of hydrogenated resin which encapsulate softer lower melting cores. In other embodiments, the hydrogenated toners allow better compatibilization of wax release agents into the toner composition by extrusion process rather than by rubber roll mill methods usually required to assure sufficient mixing of the wax with the toner composition. In other embodiments, the hydrogenated toner compositions are more resistant to decomposition by light, and are oxidatively and more chemically stable than their unsaturated counterparts. The chemical inertness of the toner compositions allows for improved tribostability to diverse charge control agents which would ordinarily react with unsaturated olefins in the toner compositions. For example, certain aluminum containing charge control agents react with olefinic butadiene double bonds. Thus, the hydrogenated toner compositions of the instant invention and their images offer the advantages of enhanced light, chemical and thermal stability by the elimination of reactive butadiene double bonds by hydrogenation. Other advantages include improved compatibility with wax release agents using extrusion processing, and improved inertness of the toner compositions to charge control agents, improved release characteristics and compatibility with VITON.RTM. and silicone fuser rolls. Other advantages include improved crease test results with fused images indicative of better fixing of xerographic images to paper. Moreover, because the glass transition temperatures of hydrogenated styrene-butadiene copolymers are often increased after hydrogenation (or by addition of hydrogen across olefinic double bonds) toner blocking behavior is improved. Hydrogenation allows increased amounts of butadiene in copolymers with styrene while maintaining a high Tg of the toner composition (near 55.degree. C.). This translates into lower minimum fix temperatures due to increased soft nonstyrenic segments in the copolymers. The tribo-aging behavior is expected to be appreciably reduced due to the increased stability of the hydrogenated materials. Elimination of double bonds in the toners by hydrogenation is expected to improve fuser roll compatibility and improve release of molten toner images from the fuser roll to paper or transparency with improved image fastness or fix to paper. Increased copier reliability is anticipated.
Hydrogenation of toner resins or toner particles is accomplished by either heterogeneous (palladium on carbon) or the homogeneous Wilkinson or Crabtree catalysts. Diimide is also an effective reducing agent for the hydrogenation of olefinic bonds at atmospheric pressure in polar and apolar solvents. The advantage to diimide is that this reagent is expected to be an effective reagent for the hydrogenation of toner composition surfaces in alcohol or water and can be used to form hydrogenated polymer shells on toner surfaces. Improved blocking temperatures and release of toner images from fuser rolls result.
Toner and developer compositions are known, wherein there are selected as the toner resin styrene acrylates, styrene methacrylates, and certain styrene butadienes including those available as PLIOTONES.RTM.. Other resins have also been selected for incorporation into toner compositions inclusive of the polyesters as illustrated in U.S. Pat. No. 3,590,000. Moreover, it is known that single component magnetic toners can be formulated with styrene butadiene resins, particularly those resins available as PLIOLITE.RTM.. In addition, positively charged toner compositions containing various resins, inclusive of certain styrene butadienes and charge enhancing additives, are known. For example, there are described in U.S. Pat. No. 4,560,635, the disclosure of which is totally incorporated herein by reference, positively charged toner compositions with distearyl dimethyl ammonium methyl sulfate charge enhancing additives. The '635 patent also illustrates the utilization of suspension polymerized styrene butadienes for incorporation into toner compositions, reference for example working Example IX.
Numerous patents are in existence that illustrate toner compositions with various types of toner resins including, for example, U.S. Pat. Nos. 4,104,066, polycaprolactones; 3,547,822, polyesters; 4,049,447, polyesters; 4,007,293, polyvinyl pyridine-polyurethane; 3,967,962, polyhexamethylene sebaccate; 4,314,931, polymethyl methacrylates; Reissue 25,136, polystyrenes; and 4,469,770, styrene butadienes.
In U.S. Pat. No. 4,529,680, there are disclosed magnetic toners for pressure fixation containing methyl-1-pentene as the main component. More specifically, there are illustrated in this patent, reference column 2, beginning at line 66, magnetic toners with polymers containing essentially methyl-1-pentene as the main component, which polymer may be a homopolymer or copolymer with other alpha-olefin components. It is also indicated in column 3, beginning at around line 14, that the intrinsic viscosity of the polymer is of a specific range, and further that the melting point of the polymer is in a range of 150.degree. to 240.degree. C., and preferably 180.degree. to 230.degree. C. Other patents that may be of background interest include U.S. Pat. Nos. 3,720,617; 3,752,666; 3,788,994; 3,983,045; 4,051,077; 4,108,653; 4,258,116 and 4,558,108.
In addition, several patents illustrate toner resins including vinyl polymers, diolefins, and the like, reference for example U.S. Pat. No. 4,560,635. Moreover, there are illustrated in U.S. Pat. No. 4,469,770 toner and developer compositions wherein there are incorporated into the toner styrene butadiene resins prepared by emulsion polymerization processes.
Furthermore, a number of different carrier particles have been illustrated in the prior art, reference for example the U.S. Pat. No. 3,590,000 mentioned herein; and U.S. Pat. No. 4,233,387, the disclosures of which are totally incorporated herein by reference, wherein coated carrier components for developer mixtures, which are comprised of finely divided toner particles clinging to the surface of the carrier particles, are recited. In U.S. Pat. Nos. 4,937,166 and 4,935,326, the disclosures of which are totally incorporated herein by reference, there are illustrated, for example, carrier particles comprised of a core with a coating thereover comprised of a mixture of a first dry polymer component and a second dry polymer component not in close proximity to the first polymer in the triboelectric series. Other patents include U.S. Pat. No. 3,939,086, which teaches steel carrier beads with polyethylene coatings, see column 6; U.S. Pat. Nos. 3,533,835; 3,658,500; 3,798,167; 3,918,968; 3,922,382; 4,238,558; 4,310,611; 4,397,935 and 4,434,220.
Semicrystalline polyolefin resins or blends thereof are illustrated in U.S. Pat. No. 4,990,424 and U.S. Pat. No. 4,952,477, the disclosures of which are totally incorporated herein by reference. More specifically, in U.S. Pat. No. 4,952,477 there are disclosed toners with semicrystalline polyolefin polymer or polymers with a melting point of from about 50.degree. to about 100.degree. C., and preferably from about 60.degree. to about 80.degree. C. with the following formulas wherein x is a number of from about 250 to about 21,000; the number average molecular weight is from about 17,500 to about 1,500,000 as determined by GPC; and the M.sub.w /M.sub.n dispersity ratio is from about 2 to about 15.
I. Polypentenes-(C.sub.5 H.sub.10).sub.x PA0 II. Polytetradecenes-(C.sub.14 H.sub.28).sub.x PA0 III. Polypentadecenes-(C.sub.15 H.sub.30).sub.x PA0 IV. Polyhexadecenes-(C.sub.16 H.sub.32).sub.x PA0 V. Polyheptadecenes-(C.sub.17 H.sub.34).sub.x PA0 VI. Polyoctadecenes-(C.sub.18 H.sub.36).sub.x PA0 VII. Polynonadecenes-(C.sub.19 H.sub.38).sub.x ; and PA0 VIII. Polyeicosenes-(C.sub.20 H.sub.40).sub.x. PA0 I. poly(styrene.sub.m -butadiene.sub.n); PA0 II. poly(styrene.sub.m -isoprene.sub.n); PA0 III. poly(styrene.sub.m -butadiene.sub.n -butene.sub.o); PA0 IV. poly(styrene.sub.m -isoprene.sub.n -isopentene.sub.o); PA0 V. poly(styrene.sub.m -butadiene.sub.n)-CO.sub.2 H; PA0 VI. HO.sub.2 C-[poly(styrene.sub.m -butadiene.sub.n)]-CO.sub.2 H; PA0 VII. poly(styrene.sub.m -butadiene.sub.n -dihalobutene.sub.o); and PA0 VIII. poly(styrene.sub.m -isoprene.sub.n -dihaloisopentene.sub.o).
Examples of specific semicrystalline polyolefin polymers illustrated in this copending application include poly-1-pentene; poly-1-tetradecene; poly-1-pentadecene; poly-1-hexadecene; poly-1-heptadecene; poly-1-octadecene; poly-1-nonadecene; poly-1-eicosene; mixtures thereof; and the like. These materials are particularly suitable for making matte or low gloss black copies and prints.
In U.S. Pat. No. 5,278,016 the disclosure of which is totally incorporated herein by reference, there are illustrated toner compositions comprised of pigment particles and resin polymer particles, and wherein the toner is subjected to halogenation resulting in the formation of a toner shell. The aforementioned toner resin particles are preferably comprised of ultra low melt resin polymers, which in embodiments possess a glass transition temperature of from about 20.degree. to about 75.degree. C., and preferably from about 33.degree. to about 60.degree. C. as determined by DSC (differential scanning calorimetry), and wherein the toner melts at from about 220.degree. to about 300.degree. F. and preferably 250.degree. F. The halogenated, especially chlorinated, encapsulating polymer surfaces can possess glass transition temperature values between about 55.degree. and 110.degree. C., and preferably from about 100.degree. to about 110.degree. C. The high glass transition temperature surfaces, or shell impart, for example, robustness to the toners. The toner core comprised of resin and pigment has, for example, a glass transition temperature of from about 20.degree. to about 110.degree. C., preferably from about 25.degree. to about 60.degree., and more preferably about 40.degree. C., thus the toner is considered a low, or ultra low melting composition. The advantages of the hydrogenated resins over the halogenated toners of U.S. Pat. No. 5,278,016 are better control of the Tg of the shell coating that encapsulates the soft core. Partial catalytic hydrogenated ultra low melt polymers are disclosed on page 20 of the aforementioned copending application. Other advantages include improved release of toned images from the fuser roll, improved oxidative, light and chemical stability of toner compositions, chemical resistance to charge control agents for improved tribo stability, and improved lubricity of the toner compositions for better release from fuser rolls without sacrificing image fix.